Pipe Flow

Saima · January 10, 2011, 12:36

Hello,

I am solving a problem for pipe flow i know inlet flow conditions such as:
Pin
Tin
mass flow rate
This flow has temp almost 700K so there is some insulation on pipe ad after some numerical calculation i found Tsurf for pipe is 477K.

Now i am giving boundary consition in CFX to find exit flow conditions.

1. At inlet i put T,P and I dont know any exit condition so i took mdot(in) = mdot(out) is it ok?

2. Secondly i dont know how to treat that wall can i impose Twall 477K? it will work? or otherwise what should i have to put.

Regards,

ghorrocks · January 10, 2011, 17:41

Sounds like you need to define a pressure inlet with T and P defined, and a mass flow rate outlet with the mass flow rate defined.

Your calculated wall temp will only apply at one location along the flow and will change as the flow temperature changes. Best to use a heat transfer coefficient boundary and let it work out the wall temperature as it goes along.

January 10, 2011, 12:36	Pipe Flow	#1
Saima Senior Member Saima Join Date: Apr 2009 Location: Canada Posts: 185 Rep Power: 16	Hello, I am solving a problem for pipe flow i know inlet flow conditions such as: Pin Tin mass flow rate This flow has temp almost 700K so there is some insulation on pipe ad after some numerical calculation i found Tsurf for pipe is 477K. Now i am giving boundary consition in CFX to find exit flow conditions. 1. At inlet i put T,P and I dont know any exit condition so i took mdot(in) = mdot(out) is it ok? 2. Secondly i dont know how to treat that wall can i impose Twall 477K? it will work? or otherwise what should i have to put. Regards,

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January 10, 2011, 17:41		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Sounds like you need to define a pressure inlet with T and P defined, and a mass flow rate outlet with the mass flow rate defined. Your calculated wall temp will only apply at one location along the flow and will change as the flow temperature changes. Best to use a heat transfer coefficient boundary and let it work out the wall temperature as it goes along.